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/*
* Copyright (C) 2013 Andrea Mazzoleni
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef __RAID_GF_H
#define __RAID_GF_H
/*
* Galois field operations.
*
* Basic range checks are implemented using BUG_ON().
*/
/*
* GF a*b.
*/
static __always_inline uint8_t mul(uint8_t a, uint8_t b)
{
return gfmul[a][b];
}
/*
* GF 1/a.
* Not defined for a == 0.
*/
static __always_inline uint8_t inv(uint8_t v)
{
BUG_ON(v == 0); /* division by zero */
return gfinv[v];
}
/*
* GF 2^a.
*/
static __always_inline uint8_t pow2(int v)
{
BUG_ON(v < 0 || v > 254); /* invalid exponent */
return gfexp[v];
}
/*
* Gets the multiplication table for a specified value.
*/
static __always_inline const uint8_t *table(uint8_t v)
{
return gfmul[v];
}
/*
* Gets the generator matrix coefficient for parity 'p' and disk 'd'.
*/
static __always_inline uint8_t A(int p, int d)
{
return gfgen[p][d];
}
/*
* Dereference as uint8_t
*/
#define v_8(p) (*(uint8_t *)&(p))
/*
* Dereference as uint32_t
*/
#define v_32(p) (*(uint32_t *)&(p))
/*
* Dereference as uint64_t
*/
#define v_64(p) (*(uint64_t *)&(p))
/*
* Multiply each byte of a uint32 by 2 in the GF(2^8).
*/
static __always_inline uint32_t x2_32(uint32_t v)
{
uint32_t mask = v & 0x80808080U;
mask = (mask << 1) - (mask >> 7);
v = (v << 1) & 0xfefefefeU;
v ^= mask & 0x1d1d1d1dU;
return v;
}
/*
* Multiply each byte of a uint64 by 2 in the GF(2^8).
*/
static __always_inline uint64_t x2_64(uint64_t v)
{
uint64_t mask = v & 0x8080808080808080ULL;
mask = (mask << 1) - (mask >> 7);
v = (v << 1) & 0xfefefefefefefefeULL;
v ^= mask & 0x1d1d1d1d1d1d1d1dULL;
return v;
}
/*
* Divide each byte of a uint32 by 2 in the GF(2^8).
*/
static __always_inline uint32_t d2_32(uint32_t v)
{
uint32_t mask = v & 0x01010101U;
mask = (mask << 8) - mask;
v = (v >> 1) & 0x7f7f7f7fU;
v ^= mask & 0x8e8e8e8eU;
return v;
}
/*
* Divide each byte of a uint64 by 2 in the GF(2^8).
*/
static __always_inline uint64_t d2_64(uint64_t v)
{
uint64_t mask = v & 0x0101010101010101ULL;
mask = (mask << 8) - mask;
v = (v >> 1) & 0x7f7f7f7f7f7f7f7fULL;
v ^= mask & 0x8e8e8e8e8e8e8e8eULL;
return v;
}
#endif
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